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  1. CircutScoper

    Advice on modifying LED light circuit

    Only guessing, of course, but perhaps "W_PWM" stands for "White _ Pulse Width Modulation" (i.e. cool LEDs) while "Y_PWM" is "Yellow _ Pulse Width Modulation." (warm LEDs). If my guess is correct, then cutting "Y_PWM" (e.g., with an added switch) would disable the warm LEDs.
  2. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Try this. Note that, in order to work, the circuit depends on the (undocumented) 555's behavior when both threshold and -trigger are simultaneously asserted, which will occur when 12V turns off. This is technically an undefined state, but it seems a "typical" LMC555 will have -trigger override...
  3. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Oops! Bad idea. Won't work because the R6 diode won't conduct and trigger the 555 until 12V decays all the way down to 1V. A better idea would be separate RC networks for the 555 trigger and threshold inputs.
  4. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Then I suggest increasing C3 as described, then adding a diode (e.g., 1N4004) in parallel with R6 with its cathode on the 12V end. That RC will give you your ~2s delay on 12V ON, while the diode will bypass the RC on 12V OFF.
  5. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    How about a software delay then? Meanwhile what does "instantaneous" mean in the context of the ~4 second discharge you measured on 12V?
  6. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    You could increase C3 to 330uF or so, but this would also delay 12V OFF. If that's acceptable, go for it.
  7. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Congratulations! I'm tempted to wonder if that was the problem all along and the 555 wasn't really necessary, but it's probably best not to even go there.
  8. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Yup. Q2 is not in the circuit. Either its emitter or its base are not connected, or neither is, or it's destroyed.
  9. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    PS: I suspect you'll see a larger amplitude negative pulse. I.e. > -2V. If you do, this will indicate Q2 is either defective or not properly connected. Most likely the latter. It's also possible that Q2's collector connections are faulty, in which case the R4&R5 negataive pulse will be normal.
  10. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    What do you see on your scope when connected to the common node of R4&R5 when you cycle 12V on/off? It should be a ~0.7V positive pulse when 12V cycles off, and ~-0.7V negative pulse when 12V cycles on.
  11. CircutScoper

    I'm seeing 5"-long caps marked "3000F"! Did they change label units??

    Indeed. A real choking hazard.
  12. CircutScoper

    electronic following circuit

    Another good reason for a mechanical connection is, if you go to the bother, expense, and complexity of providing a self-propelling power source in the "trailer," then besides the improved simplicity of guidance, if you ever got tired of towing it, then it could tow you!.
  13. CircutScoper

    I'm seeing 5"-long caps marked "3000F"! Did they change label units??

    Nope. They really mean Farads. Note the phrase "Super Capacitor." These devices store so much charge (e.g., nearly an amp-hour per volt) that they bridge the difference between regular capacitors and rechargeable batteries.
  14. CircutScoper

    A simple electric fence idea

    Just as a random-factoid thing: "Waste-spark" coils aren't really designed to waste sparks, but rather so that each coil can serve two engine cylinders operating one crankshaft rotation out of phase, thus halving the number of coils required. They came into fashion when distributors fell out.
  15. CircutScoper

    A simple electric fence idea

    Looks like a good circuit, but one modification might be a useful safety measure. The C1, D1, D2 voltage doubler has the ability to charge C2 to ~680V if L1 should fail open-circuit or the SCR circuit otherwise quit. The resulting possibility of grossly over voltaging C2 and provoking a 90J...
  16. CircutScoper

    electronic following circuit

    How 'bout a rope?
  17. CircutScoper

    Push-Pull Potentiometer Selection for Specific Electric Guitar Effects

    I have no idea what a push-pull-potentiometer might be, but I love the alliteration!
  18. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    The 555's trigger points are proportional to the 5V supply. So long as it's "close" to 5V, "12V-ON" will occur at 10V, "12V-OFF" at 5.
  19. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    I thought you said your 12V supply is giving 12.4V. That's only about 3% off. But if you think you need better, you can buy an efficient regulated switching supply for $10 or so.
  20. CircutScoper

    Generating two complementary signals on 12 V supply on/off

    Okay. How about this change of plan? Add our old friend the 555 to generate nice snappy logic transitions when 12V crosses 10V (when turning ON) and 5V (turning OFF) no matter HOW long it takes to do it. It adds complexity but avoids the transition time issue altogether.
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